Standard Treatment for Follicular Thyroid Cancer
The standard treatment for follicular thyroid cancer is total or near-total thyroidectomy followed by radioactive iodine ablation, with subsequent thyroid hormone suppression therapy. 1, 2
Initial Surgical Management
- Total or near-total thyroidectomy is the primary treatment for follicular thyroid carcinoma (FTC) when the diagnosis is made before surgery and the nodule is ≥1 cm, or regardless of size if there is metastatic, multifocal, or familial disease 1
- Less extensive procedures (lobectomy plus isthmusectomy) may be considered only in cases of unifocal, small, intrathyroidal tumors with favorable histology that are diagnosed after surgery performed for benign thyroid disorders 1
- Careful exploration of the neck by ultrasound should be performed before surgery to assess lymph node status 2
- Compartment-oriented microdissection of lymph nodes should be performed in cases of preoperatively suspected or intraoperatively proven lymph node metastases 1, 2
Post-Surgical Management
- Radioactive iodine (RAI) ablation is typically administered after surgery to ablate any remnant thyroid tissue and potential microscopic residual tumor 1, 2
- RAI therapy is particularly important for FTC with distant metastases, and can be administered after TSH stimulation (either through levothyroxine withdrawal or using recombinant human TSH) 2
- Suppressive doses of levothyroxine should be administered to maintain serum TSH levels <0.1 μIU/ml (unless contraindicated) to prevent tumor growth by inhibiting endogenous thyroid-stimulating hormone 2
Special Considerations Based on Disease Extent
- For minimally invasive follicular thyroid cancer (MIFTC), some evidence suggests that hemithyroidectomy may be adequate in selected cases with capsular invasion only and possibly for those with limited vascular invasion (≤3 foci) 3, 4
- For widely invasive follicular thyroid cancer (WIFTC) or cases with distant metastases, total thyroidectomy with RAI therapy is essential, as these patients have significantly worse overall survival 4
- For RAI-refractory disease, systemic therapy such as sorafenib should be considered 2, 5
- Bone resorption inhibitors (bisphosphonates and denosumab) may be used for thyroid cancer-related bone metastases 2
Follow-Up Protocol
- Regular monitoring with serum thyroglobulin measurements to assess treatment response and detect recurrence 2
- 2-3 months after initial treatment, thyroid function tests should be performed to check adequacy of levothyroxine suppressive therapy 2
- 6-12 months after initial treatment, screening with physical examination, neck ultrasound, and serum thyroglobulin measurement (basal and stimulated) with or without diagnostic whole-body scan 2
- Serial imaging studies including MRI, CT, or PET/CT as indicated for monitoring of known metastases 2
Clinical Considerations and Pitfalls
- The distinction between follicular adenoma and FTC is difficult preoperatively, as they share similar cytoarchitectural features 5
- For nodules with indeterminate cytology (Bethesda class III-V), molecular testing (if available) should be considered before surgery 5
- In expert hands, surgical complications such as laryngeal nerve palsy and hypoparathyroidism are extremely rare (<1-2%) 1
- Prognostic factors for FTC include distant metastasis, age, tumor size, vascular invasion, TERT promoter mutation, and histological subtype 5
- The degree of vascular invasion is becoming increasingly important for prognosis and management decisions 5, 3